Draw press for sheet metal



Dec. 16, 1924. 1,519,333

c. J. RHODES ET AL DRAW PRESS FOR SHEET METAL Fi'led Dec. 13, 1922 2 Sheets-Sheet 1 Dec, 16, 1924. 1,519,333

C. J. RHODES ET AL.

DRAW PRESS FOR SHEET METAL Filed Dec. 13, 1922 2 Sheets-Sheet 2 ivwenms Patented Dec. 16, 1924.

CHARLES JOSEPH RHODES AND GEORGE WILLIAM BERRY, 0F WAKEFIELD, ENGLAND.

DRAW PRESS FOR SHEET METAL.

Application filed December 13, 1922. Serial No. 606,742.

To all whom it may concern:

Be it known that we, CHARLns Josnrrr Rnoons and Groner. VVILLIAM BERRY, residing at VJakefield in the county of York, England, both subjects of the King of Great Britain and Ireland, have invented certain new and useful Improvements in Draw Presses for Sheet Metal, of which the fol lowing is a specification.

This invention relates to draw presses for sheet metal and more particularly to what are known as combination presses that is to say those in which the lower die is provided with a movable pressure ring usually connected by pins passing through the bed of the press and operatively connected to a resilient buffer or bumper composed of rubber and which receives the pressure exerted by the top die during the drawing operation. In such machines the pressure exerted on the pressure ring and on the bumper is a gradually increasing one as the draw progresses and in practice is much greater than is required to efiiciently draw the metal being shaped, this resulting in the resilient properties of the bumper being much impaired and its life reduced.

The present invention comprises means by which a constant pressure which may be previously determined is always maintained on the pressure ring of the lower die and consequently on the work, and in certain cases also on the bumper at all stages of the drawing operation and irrespective of the length or depth of draw being carried out.

Three forms of the present invention given as examples are illustrated in the accompanying drawin s. Figs. 1 and 2, and Figs. 3 and 4 being respectively sectional side elevation and partial end elevation of the ram and die elements and associated parts of the two forms referred to.

In the embodiment of the invention shown in Figs. 1 and 2 a rod or bar a is adjustably connected, as by means of threaded link a and nuts c to the ram 7) or other suitable moving part of the press to obtain the required movement according to dies of different depth. The ram carries the upper die 5 as usual and the rod is pivotally connected below the bed a of the press to oppositely extending links (Z (Z one of which is pivotally connected at al to the bumper e which is slidably mounted on horizontal rods, studs or the like c and the degree of compression of which can be adjusted by means of nuts c on said rods or other convenient means. The other link (Z is con nected through a quadrant (Z and rod sys tem d with a pressure platform or plate c carrying the aforesaid pins 6 connected to the pressure ring 6 of the lower die 6 The quadrant d is anchored or pivoted about a fixed point f by means of a bracket 7 carried by the body of the press and the degree of pressure desired on the pressure ring 6 and consequently on the metal being drawn can be predetermined by initially adjusting the position of the bumper on its rods or studs 6 by means of the nuts or other devices provided.

The action of such construction is as follows As the rain 6 descends, the aforesaid links cl 0Z are depressed and during this displacement no movement of any other parts takes place until the pivotal point of connection cZ between the rod a and links (Zd reaches a point which is a similar distance below the axis 6* of the bumper as it previously was above said axis. Vfhen this point reached the upper die 5 will have engaged the pressure ring 9 of the lower die which consequently descends due to the pressure of the draw action thereon and in doing so the quadrant (Z and links (Z {Z above referred to are acted on whereby the pr platform 6 connected to the pressure r g is caused to descend at the same speed as the ram but no further compression of the rubber bumper 6 takes place throughout the stroke of the press, since equal leverage of the links on both sides of the connecting rod is exerted. The pressure desired is previously determined and set as described and is maintained to the end of the drawing stroke.

In the form shown in F igs. 3 and t a link It is coupled up to the ram T) or any other suitable reciprocating or rotating member of the press in such a manner as to produce an upward motion as the press ram descends for example by means of the rod and lever connection 71. 71 The lower end of said link is pivotally connected at ii to a lever 1' anchored on a shaft '5 to which is also keyed metal, a die, a pressure ring mounted therea cam y. This cam has two faces a concentric path with radius a and an angular face with radius y which are engaged by bell crank lever which in turn is carried on a spindle 73 mounted in a bracket 73 supported on the body of the press. On the bell crank lever is mounted a coupling 75' in such a manner as to allow same to swivel and through it passes an adjusting bolt art upon which hinges the buffer plate m The buffer m is located below the press bed and directly connected to the pressure ring m of the lower die by the usual. pressure pins m.

As the ram Z) descends the upper die 5 engages the pressure ring m the pressure pins m bear upon and tend to compress the butler m but owing to the form of the cam j the buffer plate m is allowed to descend at the same rate as the ram, thus maintaining the original pressure on the die throughout the stroke. During the time the ram is descending and until the upper die engages the pressure ring, the cam periphery of the radius m engages a roller 72 of the lever is, thereby transferring no motion to the bell crank. "When however, the draw stroke takes place, the cam path of radius y engages the roller and this cam path is so shaped or timed that the butter recedes at the same speed as the ram descends, thus maintaining constant pressure also on the bumper.

The pressure desired is predetermined by adjustment of the bolt m and remains con stant due to the form of the cam path 1 For diiierent depths of drawn stampings all that is necessary is to adjust the length of the connecting link it so that when the up per die just engages the pressure ring of the lower die the cam roller is about to re cede on said cam surface.

With the constructions above described the initial pressure on the pressure ring is maintained throughout the depth of the stroke and in the form shown in Figs. 3 and l this constant pressure is also maintained on the butler thereby producing better work, prolonging the lite oi the dies and the bufier and effecting a considerable saving in power necessary to drive the machine, wear and tear being consequently diminished.

lVhat we claim as our invention and desire to secure by Letters Patent of the United States is z- 1. In a combination draw press for sheet metal, a die, a pressure ring mounted there in, a plunger for said die and ring, means for placing the pressure ring under pressure, and additional means connecting said firstnamed means with the ram for actuating the first-named means independently of the plunger.

2. In a combination draw press for sheet in, a plunger for said die and ring, means for placing the pressure ring under pressure, and additional means connecting said first-named means with the ram for actuating the first-named means independently of the plunger through a part of the downward cycle and in conjunction with the plunger through the remaining downward cycle of operation.

3-. In a combination draw press for sheet metal, the combination of a ram carrying an upper die, a lower die with which said up per die cooperates, a pressure ring mounted in said lower die, means for placing said pressure ring under pressure, and additional means connecting said first-named means with said ram for actuating the first-named means independently of the upper die.

a. In a combination draw press for sheet metal, a die, a pressure ring mounted therein, a plunger for said die and rings, a resilient butter connected to said pressure ring, means connecting said butter with said pressure ring, and additional means connecting said first-named means with the ram for actuating the first-named means independently I of the plunger.

5. In a combination draw press for sheet metal, a die, a pressure ring mounted therein, a bell crank having one arm adjustably connected to said pressure ring, a cam against which the other arm of the bell crank is adapted to bear, said cam having two surfaces, one concentric to the camaxis and the other angular thereto, and means for adjust-ably connecting said cam to. a moving part of the press.

6. In a combination draw press for sheet metal, a die, a pressure ring mounted therein, a buffer directly connected to said' pressure ring, a bell crank having one arm adjustably connected to said buffer, a cam against which the other. arm of the bell crank is adapted to bear, said cam having two surfaces, one concentric to the camaXis and the other angular thereto, and means for adjustably connecting said cam to a moving part of the press.

7. In a combination draw press for sheet metal, a die, a pressure ring mounted in said die, a plunger for said die and ring, a re silient buffer connected to said pressure ring, and means connecting said buffer with the ram for placing the pressure ring under pressure independently of the plunger..

8. A draw press for sheet metalcomprising a ram, a die, a pressure ring in said die, aplunger in said ram for said die and ring, and means connected'to said ram for placing the pressure ring under maximumpressure independently of the plunger and before the plunger contacts with the pressure ring.

9. A draw press for sheet metal, adie, a pressure ring in said die, a plunger forsaid die and ring, and means for placing the pressure ring under maximum pressure independently of the plunger and before the plunger contacts with the pressure ring.

10. In combination with a draw ress for sheet metal including a plunger an a pressure ring, a pressure device for said pressure ring comprising means for placing the pressure ring under maximum pressure before the plunger contacts with said pressure ring. In witness whereof We have signed this specification.

CHARLES JOSEPH RHODES. GEORGE WILLIAM BERRY. 

